Late-night hosts weren't able to pay tribute to Robin Williams on their shows Monday night, as their programs taped prior to the news of his death. But they made up for that on Tuesday's shows with emotional messages in honor of the actor and comedian who touched so many lives, including their own.

"He was one of a kind, one in a million. He's, like, unbelievable," "Tonight Show" host Jimmy Fallon said, his voice shaking with emotion. The late-night host, known for his impeccable impersonations, then offered his portrayal of the frenetic star to much applause.

"He was like the Muhammad Ali of comedy," Fallon added. He ended his tribute by standing on his desk, in reference to Williams' Oscar-nominated role in "Dead Poets Society," and declared, "Oh, captain, my captain, you will be missed."

TODAY's Natalie Morales on Wednesday called Fallon's homage to the beloved actor a "fitting tribute."

Conan O'Brien also offered moving words about the late actor, whom he called "the best talk show guest ever," on Tuesday's "Conan." The host shared with fans and sidekick Andy Richter a sweet tale about how when O'Brien was publicly going through "a bump in the road" five years ago, Williams sent him "the most absurd bicycle you'd ever seen" to cheer him up.

Though O'Brien offered a full tribute on Tuesday's show, he did address the actor's death on Monday's episode. In fact, he broke the news to his studio audience.

"Late Night" host Seth Meyers talked about how when he was younger, he worked in a video store and would rent Williams' stand-up albums regularly. "He brought me a great amount of joy," the former "Saturday Night Live" star said.

"The saddest part of this is that Robin was battling depression," Meyers also noted. "If there's anything we can do to honor his memory, I would hope it would be to use this opportunity to educate us more about this affliction."

Several of the other popular late-night programs are in reruns this week, but the shows and their hosts still found ways to remember the actor.

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Robin Williams, 1951-2014

"Na-nu Na-nu" and "O Captain, my Captain": Robin Williams will best be remembered by the characters he played and lines he delivered.

Robin Williams, 1951-2014

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"Mork and Mindy" -

"I am Mork from Ork, na-nu na-nu." Robin Williams' breakout role was as happy alien Mork on the TV show "Mork and Mindy," a spin-off of "Happy Days." He played Mork, and is seen sitting on set here in April 1978.

ABC via AP / ABC via AP

Robin Williams, 1951-2014

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Forever a funnyman -

Williams' Mork and Pam Dawber's Mindy were one of the most unlikely super-couples of the 1970s. They even eventually had a child, Mearth -- hatched from an egg laid by Mork and played by veteran funnyman Jonathan Winters.

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"Dead Poets Society" -

In "Dead Poets Society," Williams played English teacher John Keating, who dared his class to take risks and break out of the molds their families may have put them in. He encouraged his students to call him "O Captain! My Captain!"

Courtesy Everett Collection / Courtesy Everett Collection

Robin Williams, 1951-2014

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"Mrs. Doubtfire" -

Robin Williams played the title role in "Mrs. Doubtfire." In a TODAY interview at the time, Robin Williams told Gene Shalit that creating his character had a lot to do with the makeup he wore. In April 2014, there were reports that Williams would reprise his role in a sequel.

20th Century-Fox via Getty Images / 20th Century-Fox via Getty Images

Robin Williams, 1951-2014

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"Good Will Hunting" -

Williams, right, next to Matt Damon, won an Academy Award for Best Supporting Actor in 1998 for his role in "Good Will Hunting."

Robin Williams, 1951-2014

In the 1995 fantasy-adventure film "Jumanji," Williams is chased by a lion, fights off giant spiders and is sucked into quicksand-like floorboards.

Getty Images / Getty Images

Robin Williams, 1951-2014

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"Night at the Museum" -

Williams played President Teddy Roosevelt in the "Night at the Museum" trilogy. He finished shooting the third film, "Night at the Museum: Secret of the Tomb" earlier this year. It's set to be released Dec. 19.

Twentieth Century Fox via AP / Twentieth Century Fox via AP

Robin Williams, 1951-2014

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'Flubber' -

In 1997's "Flubber," a remake of the 1961 Disney comedy "The Absent-Minded Professor," Williams played a professor with an ingenious, if trouble-prone, invention.